The present invention relates to a radiation image detecting apparatus, and more particularly to an apparatus for detecting a radiation image such as an X-ray image with the image divided into pixels.
In an ordinary system of detecting an radiation image with the image once divided into pixels, a two-dimensional array of unit radiation sensors corresponding to the pixels is positioned so that a radiation image to be detected may be projected properly thereon, or such a two-dimensional sensor array is replaced with a one-dimensional sensor array devised so as to mechanically sweep the (imaginary image-receiving) plane with which the above two-dimensional sensor array should be positioned coincidently. The signals outputted from the unit radiation sensors, which signals are pixel signals, are purposefully processed with electronic circuits so as to be displayed as a visualized radiation image on a CRT screen. In such a radiation image detecting system, the resolving power of a detected radiation image depends on the size of the unit radiation sensors used in the above two- or one-dimensional sensor array. A typical size of the unit sensors is selected to be about 0.3 mm square for a typical dimension 30 cm.sup.2 of the radiation image to be detected. This causes the number of sensors to lie in the order of 10.sup.3 (for the one-dimensional sensor array) to 10.sup.6 (for the two-dimensional sensor array). Such a numerous number of sensors are further followed by the same number of lead circuits to lead the output signals to the separately provided signal processing electronic circuits. In the above constitution of the system, therefore, the disposition of a large number of lead wires, though bundled in the form of a single cable, provides some severe problems to be solved, especially in the case where the radiation detection is carried out with a one-dimensional sensor array which is made to sweep the radiation image receiving plane. In addition, long wiring of the lead wires is liable to pick up external noise. A conventional way of overcoming the above disadvantages is to to combine each of the unit radiation sensors with a respective signal processing electronic circuit so as to constitute a composite radiation detector unit as shown in FIG. 5. Many such composite radiation detector units are closely arrayed one-dimensionally or two-dimensionally with only the radiation sensors exposed. Referring to FIG. 5, a radiation sensor 1 is accompanied by a semiconductor chip 3 provided, on its upper surface, with an integrated circuit for processing the signal outputted from the radiation sensor 1. The output from the the integrated circuit is led out through a lead circuit printed on a printing base 5 extending over other composite radiation detector units arrayed in the direction vertical to the sheet on which FIG. 5 is drawn. Although such a radiation image receiving means makes the system free from a numerous number of lead wires connecting between radiation sensors and electronic circuits, the close array of composite radiation detector units is inevitably accompanied by a large heat generation. The heat generation, which deteriorates the performance of the electronic circuits contained and often damages the circuits, is conventionally suppressed by means of forced air-cooling or by operating the system intermittently. However, the method of air-cooling is not only ineffective but also liable to give vibrations to the array of composite radiation detector units, while the intermittent operation of the system causes a series of successive radiation image detecting work to be kept at low efficiency. In addition, since the intermittent operation is still accompanied by a low level heat generation, the electronic circuits are necessarily provided with any means for compensating possible performance deterioration of the circuits.